Should fan fiction count ever towards reading goals?

Today I want to discuss something near and dear to my heart: fan fiction. Okay, to be honest I don't read a ton of fanfic, but when I do they're always really lengthy and well done.

As you may know, I love retellings. My absolute favorite are Peter Pan retellings. More specifically, Hook retellings. Unfortunately, these are few and far between in the book world (for some reason I cannot fathom). There do happen to be quite a few amazing ones online, however, and I certainly seek them out.

For some reason, fan fiction seems to be a touchy subject. To be fair, some of it is bad. Like, really bad. Some of it comes with embarrassingly bad artwork and really cheesy descriptions. Some people are embarrassed to even talk about it! No matter what though, fanfic takes just as much effort to read as any other book.

According to one source I checked out, the sweet spot for YA novels is about 60,000 words. Another source suggested 50,000 - 80,000 words. Some of the most reviewed works of fan fiction on Fanfiction.net are more than 200,000 words long and many of the stories on Wattpad are as long if not longer than most of the YA books I read.

Some of the most popular books around started out as fan fiction. A couple come immediately to mind. The Mortal Instruments series began as an 895,000 word Harry Potter fan fiction called the Draco Trilogy. Meanwhile, Fifty Shades of Grey started as an 846 page Twilight fan fiction called Master of the Universe.

While I happen to hate both these series, there's no denying that they were popular enough online to gain massive fanbases and grow into impressive traditionally published fandoms.

My question is this: when many fanfics and other online stories are 60,000+ words, longer than a lot of YA novels (and sometimes of better quality), should they be counted towards yearly reading goals or even things like read-a-thons? If I'm essentially reading an extra book each week, why shouldn't I plug it into my challenge tracker?